exim's default mail server IP - can it be dynamic?

All emails sent from my machine goes thru nobody, which is ok, knowing that I didnt install phpsuexec - but can it somehow use dynamic IP for sending emails (for instance - the account owners one) istead of my main IP which is used in all emails - I dont want my main server IP compromised by spammers (I had to terminate one account yesterday, but it was too late, guy already sent thousands of emails) and beside all other thing, Im really interested in those exims IP settings. I can bind Exim to some other IP thru its conf, but is it possible to use much more than 1 IP (as I said, using account owners IP would be best) -- I assume phpsuexec doesnt offer that ability, it just changes user under which PHP runs, but thats irrelevant to exims IP, right?

I don't believe that you can do that. As you say, you can change the IP address that Exim binds to for both incoming or outgoing connections, but AFAIK, it's a one shot deal. Might have a peek over at exim.org to see.